I. Field of the Invention
The present invention relates to rinse-added treatment compositions for fabrics, in particular, compositions for the hand rinsing of fabrics as well as the rinsing of fabrics in top loaded non-automated washing machines as well as automated washing machines after the fabrics have been laundered with a detergent composition. The present invention also relates to methods for increasing the rinsing capacity of aqueous rinse bath solutions as well as methods for removing greater quantities of laundry residue from laundered fabrics than is achieved in rinse baths consisting only of water. Further, the present invention relates to laundry rinse bath solutions with improved rinsing capacity.
II. Description of the Prior Art
The trend for washing is to use a washing machine wherein the laundry detergent and a fabric softening composition are dispensed from the washing machine via two separate compartments, thereby ensuring the automated release of the detergent at the beginning of the washing process and the release of the softening composition in the rinse process, usually near the end of the rinse process, or where multiple rinses are selected, during the final rinse process.
In most countries under development, the consumer's washing habit is to wash their garments with either non-automated top loaded washing machines (i.e. apparatus which comprises two separated cubicles, one for washing or rinsing, and one for spinning), or in basins or buckets. The washing in basins or buckets involves a manual operation with the multiple cumbersome steps of damping the fabrics, washing with detergent, wringing, and rinsing one or more times with water. Similarly, when washing in non-automated top loaded washing machines, the washing is operated by placing the fabric with detergent in the cubicle containing water, providing agitation, removing the fabrics from the cubicle containing the detergent liquor, placing the fabric in the spinning cubicle for spinning step, empty the detergent liquor from the other cubicle and replace it by fresh water and then put back the spinned fabrics for rinsing. The rinsing step of spinning, rinsing, and spinning being often reiterated several times to obtain acceptably rinsed fabrics. As such rinsing is usually done with clean water, this method of rinsing can be a major problem in regions experiencing water shortages.
Further, hand-washing is not limited to any particular geographical region. Although certain areas having limited access to modern appliances have a higher prevalence of hand washing, the need for hand-washing, including manual rinsing, is universal at least with respect to certain items of clothing and fabric articles. Hence, even with modern washing machines having a dedicated rinsing step, there are still many garments, especially those manufactured from “fine fabric” material (i.e. silk) or those which comprise “soft woven” material (i.e. woolen knitted sweaters) that are commonly “laundered by hand”. “Delicates” and/or “personal” articles typically require hand-washing for proper care.
There are several disadvantages associated with hand washing. Foremost, hand washing typically limits the temperature at which the fabrics are washed, usually within a range tolerable to the person washing the garment. In addition, hand washing and/or washing in non-automated top loaded washing machines, typically is accompanied by high detergent to water ratio and/or high soil to water ratio (high soil loading). During such laundering the fabrics usually become saturated with residual detergent and/or dirt and particulate matter upon transfer to the rinse step.
Although this saturation problem is more acute with manual washing and/or washing in non-automated top loaded washing machines, it is also a problem for automated washing machines when the rinsing process is too short or is inefficient due to the characteristics of the particular articles being laundered. For instance, it is not uncommon in automated machines for the consumer to overload the machine or to program too little water for the amount of fabrics being laundered. In either case, the fabrics will not be thoroughly rinsed at the completion of the rinse cycle. Automated machine washing is also characterized by a high detergent to water ratio such that laundered fabrics are commonly saturated with residual detergent at the beginning of the rinse cycle.
Further, the use of conventional detergent products such as the so called “High Suds Detergents” in any washing method commonly results in suds being carried over to the rinse bath solution requiring additional time, energy and water to thoroughly rinse the laundered fabrics.
The conservation of resources such as energy and water is not to be underestimated. These types of resources are being stretched to their limits in many communities around the world. The majority of the water used in a typical laundering process is consumed during one or more rinsing cycles. As such, governments are beginning to provide incentives to washing machine manufacturers to reduce the amount of water that is consumed in each laundry process. Because of the disproportionate amount of water that is used during the rinse cycle(s), the industry is searching for ways to make the rinsing process more efficient, preferably by shortening rinse times and/or by reducing the number of rinse cycles.
Historically, rinse-added fabric treating compositions were not intended to improve the efficiency or rinsing capacity of the rinse bath solution, but rather were in the nature of laundry “sours” that contained a neutralizing agent, typically a mild acid, to neutralize the pH of the highly alkaline wash liquor. It was believed that staining of fabrics in the rinse from iron and rust could be avoided by rapidly neutralizing the pH of the rinse bath solution. U.S. Pat. No. 3,676,353 discloses such a laundry sour composition.
As the use of fabric softening compounds and compositions developed, cationic fabric softener actives were added to laundry sour compositions as disclosed in U.S. Pat. Nos. 3,637,495, 3,644,204 and 3,904,359. Similarly, U.S. Pat. No. 4,814,095 discloses an after-wash treatment composition that utilizes a layered silicate as the softening component of the composition. Again, however, none of these compositions are directed at improving the efficiency of the rinse or increasing the capacity of the rinse bath solution to remove foreign materials from the laundered fabrics.
U.S. Pat. No. 4,828,750 to Simion, et al., granted on May 9, 1989 discloses an fabric rinse composition for allegedly removing residual soap and surfactants left on clothes during washing. This composition consists essentially of low levels of nonionic surfactant and an organic acid to allegedly remove the residual soap and surfactant from fabrics (i.e., wool) which remain after it has already been rinsed with hard water (see, e.g., col. 5, lines 6-11). However, this composition is not directed to reducing water use, reducing suds, and/or improving rinse bath solution clarity.
More recently, Japanese Patent Application No. JP 10219297 discloses an after-treatment agent for commercial laundry washing that comprises a polycarboxylic acid for neutralizing the highly alkaline wash or rinse bath solutions. However, similar to the laundry sours, this composition focuses on reducing the pH of the laundry solutions to neutrality or approximately 7.
Accordingly, there is a need for methods and compositions that will relieve or ease the burden of washing by providing a more efficient rinse bath solution that will allow the consumer to thoroughly rinse their laundered fabrics in a single rinse process as well as aid in reducing the amount of water and energy that is consumed in the laundering process.
There is also a need for methods and compositions that can improve the removal of foreign materials and laundry residue from fabrics. The removal of these residues tends to restore fabrics to their natural softness and feel as well as restoring their whiteness and colors, thereby enhancing the cleaning effect of the overall laundry process.
Furthermore, the removal of laundry residues also removes allergens and skin irritants that might have been deposited on the fabrics during previous wear or during the laundering process.
Likewise, there is a need for methods and compositions that provide for the complexing of metal ions in solution, particularly when water contaminated with heavy metal ions is used. Indeed, water contaminated with heavy metal ions is often the cause of re-soiling on fabrics during the rinse.